A flexible hierarchical nanoporous high entropy alloy and preparation method thereof

Abstract

The present invention discloses a preparation method of a flexible hierarchical nano-porous high-entropy alloy, comprising the following steps: 1) Preparation of alloy powder materials, mixing Cu, Al, Ni, Mo, and Fe powders in different proportions, and obtaining alloy powder materials for plasma cladding with different components through high-energy ball milling; 2) Preparation of high-entropy intermetallic compound foil strips, using the plasma cladding process to clad on the surface of a 45 steel substrate to obtain a high-entropy intermetallic compound coating. 3) Preparation of the flexible hierarchical nano-porous high-entropy alloy, putting the foil strips into a 0.1 mol / L KOH solution, taking them out after corrosion at a temperature of 50 °C for 2 h, and repeatedly rinsing with alcohol and deionized water to obtain the hierarchical nano-porous high-entropy alloy. Compared with the traditional preparation methods of high-entropy alloys (chemical methods or smelting processes), the high-energy ball milling method of the present invention has a simple process and low cost; through plasma cladding and cutting rolling, an integrated high-entropy intermetallic compound foil strip is obtained, realizing the strong metallurgical bonding performance between the high-entropy alloy and the substrate. d , b , c , e , a , c , d , a , b , e Ni b Mo c Fe d Al e Preparation of alloy powder materials, mixing Cu, Al, Ni, Mo, and Fe powders in different proportions, and obtaining alloy powder materials for plasma cladding with different components through high-energy ball milling; a Ni b Mo c Fe d Al e Preparation of high-entropy intermetallic compound foil strips, using the plasma cladding process to clad on the surface of a 45 steel substrate to obtain a high-entropy intermetallic compound coating. 3) Preparation of the flexible hierarchical nano-porous high-entropy alloy, putting the foil strips into a 0.1 mol / L KOH solution, taking them out after corrosion at a temperature of 50 °C for 2 h, and repeatedly rinsing with alcohol and deionized water to obtain the hierarchical nano-porous high-entropy alloy. Compared with the traditional preparation methods of high-entropy alloys (chemical methods or smelting processes), the high-energy ball milling method of the present invention has a simple process and low cost; through plasma cladding and cutting rolling, an integrated high-entropy intermetallic compound foil strip is obtained, realizing the strong metallurgical bonding performance between the high-entropy alloy and the substrate.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of materials for hydrogen evolution by electrolysis of water, and in particular to a flexible hierarchical nanoporous high-entropy alloy and a preparation method thereof. Background Art

[0002] At present, my country's carbon peak and carbon neutrality development goals will further accelerate the process of carbon reduction. Hydrogen energy, as a zero-carbon energy carrier, has shown broad application prospects in energy storage, metallurgy, distributed power generation and other fields. Using renewable energy to electrolyze water to produce hydrogen can avoid CO 2 The emission of green hydrogen is a typical way to produce green hydrogen. The United States and China have successively issued policies to plan green hydrogen manufacturing and promote the green and low-carbon transformation of energy. Hydrogen production by water electrolysis involves two half reactions: cathode hydrogen evolution (HER) and anode oxygen evolution (OER). In HER, hydrogen evolution electrocatalyst is the key to directly affecting hydrogen yield and stability. Therefore, the development and design of efficient hydrogen evolution electrocatalysts is crucial.

[0003] Among them, high entropy alloys have broad application prospects in improving the catalytic performance and stability of cathode hydrogen evolution during water electrolysis due to their unique cocktail effect, high entropy effect, lattice distortion effect and hysteresis diffusion effect. However, there are still two major problems in the use of high entropy alloys. First, the electrode structure is not ideal: especially the bulk and powdered high entropy alloys have few catalytic active sites and are not conducive to the electron / ion and H in the hydrogen evolution process. 2 The transport of molecules. ad The binding energy regulation mechanism is unclear: According to the hydrogen evolution reaction mechanism, the intermediate product adsorbed hydrogen (H ad ) binding energy is the key to hydrogen-hydrogen bonding, while the regulation of the electronic structure of the catalyst surface and the catalytic activity are the factors affecting H ad However, due to the multi-component metal elements, the complexity of the electronic structure and catalytic active sites of high entropy alloys affects the H ad Regulation of binding energy.

[0004] In response to the above problems, the researchers found that coupling the electronic structure of the catalyst surface to regulate and improve the catalytic active sites to H ad The optimization of adsorption energy is the most effective and easy to implement. Li et al. found through calculation that the synergistic effect between various elements in high entropy alloys can effectively modify the d-band center, directly managing the adsorption and activation of intrinsic activity and intermediates. On this basis, Jia et al. found that nanostructured high entropy alloys can increase the catalytic active sites and further reduce the generation of H by water decomposition of alkaline electrolytes. ad Energy barrier, promoting H ad Coupling to generate H 2 However, the use of binder / Nafion blocks the electrons / ions and H 2Molecular transport. These studies show that hierarchical porous high entropy alloys with an integrated structure are more likely to meet the requirements of high-performance hydrogen evolution catalysts. However, the conventionally prepared hierarchical porous high entropy alloys have obvious macroscopic brittleness due to abundant pore defects. The present invention achieves metallurgical bonding of the high entropy alloy layer and the substrate by plasma cladding the high entropy alloy on the surface of the metal substrate; then a dealloying process is used to construct a rich hierarchical nanoporous structure on the high entropy alloy layer. The characteristic of this method is that it not only achieves the purpose of strong interface bonding between the hierarchical nanoporous high entropy alloy and the metal substrate, but also satisfies the high catalytic activity of the hierarchical nanoporous high entropy alloy. Summary of the invention

[0005] The purpose of the present invention is to provide a flexible hierarchical nanoporous high entropy alloy for electrocatalytic water decomposition and a preparation method thereof. a Ni b Mo c Fe d Al e High entropy intermetallic compounds (including high entropy CuNiMoFe, α-Al, CuAl 2 phase, and a+b+c+d+e=100) is used as the base material, and the high-entropy alloy phase is retained by dealloying to obtain a graded nanoporous high-entropy alloy. The preparation method is simple in process and low in cost. The prepared flexible graded nanoporous high-entropy alloy has excellent electrocatalytic performance and is suitable for industrial production.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is: a method for preparing a flexible hierarchical nanoporous high entropy alloy, characterized in that it comprises the following steps:

[0007] 1)Cu a Ni b Mo c Fe d Al e Preparation of alloy powder

[0008] Pure metal powders of Cu, Al, Ni, Mo and Fe are mixed in different proportions, and alloy powders of different components for plasma cladding are obtained by high-energy ball milling;

[0009] In a preferred embodiment, in the alloy ratio, the content of Al is between 60% and 85%, and the proportion of other metal components is between 1% and 20%;

[0010] In a preferred embodiment, the high energy ball milling speed is 1000 to 1500 rpm, and the ball milling time is 10 to 24 hours.

[0011] 2)Cu a Ni b Mo c Fed Al e Preparation of high entropy intermetallic compound foil

[0012] The obtained alloy fractions are clad on the surface of a 45 steel substrate by a plasma cladding process to obtain a high entropy intermetallic compound coating, and then the high entropy intermetallic compound coating is cut and rolled to obtain a foil strip.

[0013] In a preferred embodiment, the conditions for plasma cladding are arc voltage (35-45 V), current (100-150 A) and powder feeding speed (10-20 g·min -1 );

[0014] In a preferred embodiment, the thickness of the foil strip after cutting and rolling is 50 to 300 μm.

[0015] 3) Preparation of flexible hierarchical nanoporous high entropy alloys

[0016] The foil strip in step 2) is immersed in a 0.1 mol / L KOH solution at a corrosion temperature of 50° C. for 2 h, then taken out and repeatedly rinsed with alcohol and deionized water to obtain a graded nanoporous high entropy alloy.

[0017] In a preferred embodiment, the etching solution is KOH, NaOH, NaHCO 3 One or more of the following, or a mixed solvent thereof;

[0018] In a preferred embodiment, the concentration of the etching solution is 0.1 to 5 mol / L;

[0019] In a preferred embodiment, the corrosion temperature is 20 to 100°C;

[0020] In a preferred embodiment, the corrosion time is 2 to 48 hours.

[0021] The present invention regulates the pore structure by regulating the high entropy alloy composition and chemical dealloying parameters (corrosive liquid type, concentration, dealloying time, temperature, etc.), thereby obtaining a flexible hierarchical nanoporous high entropy alloy. As a functional material, it has great development potential in the field of electrocatalysis.

[0022] The advantages of the present invention compared with the prior art are:

[0023] 1) Compared with the traditional high entropy alloy preparation method (chemical method or smelting process), the high energy ball milling method of the present invention is simple in process and low in cost;

[0024] 2) The integrated high-entropy intermetallic compound foil strip is obtained by plasma cladding and cutting and rolling, achieving strong metallurgical bonding performance between the high-entropy alloy and the substrate;

[0025] 3) A hierarchical nanoporous high-entropy alloy was obtained by a one-step dealloying method. The existence of hierarchical pores not only improves the ion / electron transfer efficiency, but also increases the specific surface area of ​​the material, exposing more active sites, thereby improving the catalytic activity (10 mA cm -2 The overpotential Δφ under current density is 20~100mV; the stability is about 20h). BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the plasma cladding preparation flow chart of the present invention.

[0027] Figure 2 It is a metallographic diagram of the substrate-supported high-entropy alloy generated by cladding according to the present invention.

[0028] Figure 3 This is a microscopic morphology of the hierarchical pores after dealloying of the present invention. DETAILED DESCRIPTION

[0029] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0030] Example 1

[0031] The metal powders were prepared according to the atomic ratio of Cu 10%, Ni 10%, Mo 10%, Fe 10% and Al 60% (powder particle size 60 microns), and then ball milled at a high energy ball mill speed of 1000 r / min for 10 hours to obtain Cu 10 Ni 10 Mo 10 Fe 10 Al 60 Alloy powder; plasma cladding process is used to control arc voltage 35V, current 120A) and powder feeding speed 10g·min -1 , Ni@Cu supported by Ni is obtained by cladding on pure metal Ni substrate 10 Ni 10 Mo 10 Fe 10 Al 60 The composite alloy was then dealloyed with 1 mol / L NaOH alkaline solution to obtain a Ni-supported flexible hierarchical nanoporous Ni@CuNiMoFe electrode. In the cathode hydrogen evolution electrocatalytic test in 1 mol / L KOH electrolyte, 10 mA cm -2 The overpotential Δφ is 71mV at a current density of 100mA·cm -2 The overpotential Δφ is 311 mV at a current density of , and the overpotential does not increase after 20 hours of cycling.

[0032] Example 2

[0033] The metal powders were prepared according to the atomic ratio of Cu 4%, Ni 4%, Mo 4%, Fe 4% and Al 84% (powder particle size ~ 60 microns), and then ball milled at a high energy ball mill speed of 1000r / min for 10 hours to obtain Cu 4 Ni 4 Mo 4 Fe 4 Al 84 Alloy powder; plasma cladding process is used to control arc voltage 35V, current 120A) and powder feeding speed 10g·min -1 , Ni@Cu supported by Ni is obtained by cladding on pure metal Ni substrate 4 Ni 4 Mo 4 Fe 4 Al 84 Composite alloy; Finally, 1 mol / L NaOH alkaline solution was used for dealloying to obtain Ni-supported flexible hierarchical nanoporous Ni@CuNiMoFe-2 electrode. In the cathode hydrogen evolution electrocatalytic test in 1 mol / L KOH electrolyte, 10 mA cm -2 The overpotential Δφ is 65mV at a current density of 100mA·cm -2 The overpotential Δφ is 292 mV at a current density of , and the overpotential does not increase after 20 hours of cycling.

[0034] Example 3

[0035] The metal powders were prepared according to the atomic ratio of Cu (7%), Ni (2.5%), Mo (7.5%), Fe (3%) and Al (80%) (powder particle size ≈ 60 μm), and then ball milled at a high energy ball mill speed of 1000 r / min for 10 hours to obtain Cu 7 Ni 2.5 Mo 7.5 Fe 3 Al 80 Alloy powder; plasma cladding process is used to control arc voltage 35V, current 120A and powder feeding speed 10g·min -1 , Ni@Cu supported by Ni is obtained by cladding on pure metal Ni substrate 7 Ni 2.5 Mo 7.5 Fe 3 Al 80 Composite alloy; finally, 1 mol / L NaOH alkaline solution was used for dealloying to obtain Ni-supported flexible hierarchical nanoporous Ni@CuNiMoFe-3 electrode. In the cathode hydrogen evolution electrocatalytic test in 1 mol / L KOH electrolyte, 10 mA·cm-2 The overpotential Δφ is 47 mV at a current density of 100 mA·cm -2 The overpotential Δφ is 284 mV at a current density of , and the overpotential does not increase after 40 hours of cycling.

[0036] Example 4

[0037] The metal powders were prepared according to the atomic ratio of Cu (7%), Ni (2.5%), Mo (7.5%), Fe (3%) and Al (80%) (powder diameter ~60 μm), and then ball milled at a high energy ball mill speed of 1800 r / min for 20 hours to obtain Cu 7 Ni 2.5 Mo 7.5 Fe 3 Al 80 Alloy powder; plasma cladding process is used to control arc voltage 45V, current 133A and powder feeding speed 25g·min -1 , Ni@Cu supported by Ni is obtained by cladding on pure metal Ni substrate 7 Ni 2.5 Mo 7.5 Fe 3 Al 80 Composite alloy; finally, 1 mol / L NaOH alkaline solution was used for dealloying to obtain Ni-supported flexible hierarchical nanoporous Ni@CuNiMoFe-3 electrode. In the cathode hydrogen evolution electrocatalytic test in 1 mol / L KOH electrolyte, 10 mA·cm -2 The overpotential Δφ is 42 mV at a current density of 100 mA·cm -2 The overpotential Δφ is 281 mV at a current density of , and the overpotential does not increase after 40 hours of cycling.

[0038] The present invention and its implementation methods are described above, and such description is not restrictive. The specific implementation methods are only part of the embodiments of the present invention, not all of the embodiments, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and implementation method similar to the technical solution without creativity, which should fall within the protection scope of the present invention.

Claims

1. A method for preparing a flexible hierarchical nanoporous high entropy alloy, characterized in that: The following steps are involved: 1)Cu a Ni b Mo c Fe d Al e Preparation of alloy powder Pure metal powders of Cu, Al, Ni, Mo and Fe are mixed in different proportions, and alloy powders of different components for plasma cladding are obtained by high-energy ball milling; 2)Cu a Ni b Mo c Fe d Al e Preparation of high entropy intermetallic compound foil The obtained alloy powder is clad on the surface of 45 steel substrate by plasma cladding process to obtain high entropy intermetallic compound coating; The high entropy intermetallic compound coating is then cut and rolled to obtain a foil strip; 3) Preparation of flexible hierarchical nanoporous high entropy alloys The foil strip in step 2) is immersed in a 0.1 mol / L KOH solution at a corrosion temperature of 50° C. for 2 h, then taken out and repeatedly rinsed with alcohol and deionized water to obtain a flexible hierarchical nanoporous high entropy alloy; In the step 1), the content of Al in the metal powder is between 60% and 85%, and the content of other metal components is between 1% and 20%.

2. The method for preparing a flexible hierarchical nanoporous high entropy alloy according to claim 1, characterized in that: In the step 1), the high-energy ball milling speed is 1000-1500 rpm, and the ball milling time is 10-24 hours.

3. The method for preparing the flexible hierarchical nanoporous high entropy alloy according to claim 1, characterized in that: The conditions of plasma cladding in step 2) are: arc voltage of 35-45V, current of 100-150A, powder feeding speed of 10-20g / min -1 ; The thickness of the foil strip after cutting and rolling is 50~300μm.

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